Field of the Invention
The present invention relates to a holding apparatus for holding a cable, particularly a grounding cable or shielding cable, as typically used for cable passages or cable introductions in housings of devices or control cabinets.
Discussion of Related Art
Such holding apparatuses can serve, on the one hand, for tension relief with a sealing function of the cable, and, on the other hand, for electromagnetic shielding, and for conducting away line interference. For this purpose, the cable is axially secured in the holding apparatus, and an electrical contact with a cable shielding, which generally consists of a wire braid disposed underneath an outer insulation of the cable, is produced. Common holding apparatuses generally comprise a sleeve-shaped base part that is disposed over a cable, a contact part and/or holding part, which holds the cable and, if necessary, can produce a contact with the cable shielding, and a connector part that can be connected with the base part and positions the contact part/holding part in the base part. The base part can be configured as a screw sleeve and can enter into a screw connection with a housing, for example, so that the cable is fixed in place on the housing.
From EP 1526620 B1 or DE 202009013522 U1, for example, cable screw connections for shielded cables are known, in which a contact part is provided with multiple elastic contact brackets disposed in ring shape, which run essentially at a slant to the longitudinal cable direction, with the bracket ends being directed toward the cable axis. The contact part is disposed within a threaded connector, which can be screwed into a housing. The contact part enters into an electrical connection with the threaded connector. A pressure element, such as a retainer nut, can be screwed onto the threaded connector, thereby narrowing an inside diameter of a holder or seal, for example. In this connection, the pressure element can also act on the contact brackets in such a manner that their ends are pressed radially inward onto the cable shielding, thereby making it possible to produce an electrical contact with the shielding. Alternatively, the bracket ends can already drag over the cable when the cable is pushed in, and be bent upward by it.
To affix the cable screw connection to the cable, the cable mantle must be removed in certain places, so that the cable shielding is exposed. After the shielding is exposed, the cable is pushed through the contact bracket ring in the axial direction, and in the case of larger cables, for example, the contact brackets can rub on the wire braid in the planned clamping region. In this connection, the danger exists that individual regions of the braid are damaged or pushed back, and that the electrical contact is disadvantageously impaired. Furthermore, the cable cannot be rotated within the contact bracket ring, because when this happens, the edges of the brackets could also damage the braid. Furthermore, the cable cannot be pulled back out of the contact bracket ring, because in this case, the tips of the brackets ends would bore into the braid and could damage it. For this reason, the braid ends are generally covered in a separate work step, for example with an adhesive tape or with conductive material. Such a type of cable screw connection is also evident from U.S. Pat. No. 4,022,966. In the case of cables having a small diameter, contact between the threaded connector and the cable is generally ensured when the cable is already accommodated in the interior of the threaded connector and the retainer nut, and the contact brackets are pressed down by means of the retainer nut. Because no defined axial positioning is provided, the possibility exists that the contact brackets are fixed in place not above an exposed braid region, but rather above the cable mantling, and no electrical contacting takes place. In the case of very thin cables, in particular, there is the risk that a radial movement of the contact brackets when the threaded connector and the retainer nut are screwed together is not sufficient to press the contact bracket ends down onto the braid.
In DE 102006052090 A1, a cable screw connection for shielded cables is shown, which is suitable for accommodating multiple cables. A double-threaded connector can be inserted into a housing with a first thread. A second thread is screwed together with a cap nut, and thereby, with an increasing screw connection, cross-sections of multiple cable passages in the squeeze seal are narrowed, and therefore the cables are axially fixed in place. To produce a connection of the cable shield with the double-thread connector, a contact insert is provided, which has a plurality of electrically conductive clamping clips, which are arranged by a holding pin to produce multiple clamping arrangements. The clamping clips are disposed around the holding pin in the circumference direction, so that two arms of adjacent clamp clips, in each instance, form a clamping arrangement, in each instance, and can be elastically bent open relative to the holding pin, to accommodate a cable. The ends of the clamping clip arms are bent inward, so that the totality of the clamping clips disposed in the circumference direction form a contact surface for a contact with the double-threaded connector.
In this embodiment of a cable screw connection, multiple clamping clips are required not only to contact the cable shielding but also to contact the double-threaded connector, and these must be mounted in an additional holder, so that they can be held together by the latter. A clamping clip alone can neither accommodate a cable nor ensure secure positioning within the double-threaded connector.